JPH05174394A - Access method for disk device - Google Patents

Abstract

PURPOSE:To shorten the access time of a disk device by defining the actual access correction distance as the correction value if the relevant access correc tion distance is different from the actual access correction distance by the prescribed value or more. CONSTITUTION:The access correction value DELTAx is added to an access distance DELTAx between the present position of a record/reproduction head and a target access position. Thus a virtual access distance X is obtained and a target access running velocity Vref is calculated from the distance X. Then the record/ reproduction head is moved at the velocity Vref so that the distance X is set at 0. Under such conditions, the actual access position of the record/reproduction head is checked and the distance DELTAx is corrected based on the actual access position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive access method for moving a recording / reproducing head to a target track (access target position) on a disk.

[0002]

2. Description of the Related Art In a disk device using a disk-shaped recording medium (disk), shortening the time required to move the recording / reproducing head to a target track on the disk is to increase the capacity of the disk and the data transfer rate. It can be said that it will be an important issue in the future as well as improving Conventionally, various methods have been proposed as methods for shortening access time. For example, by utilizing modern control theory, various states are detected and feedback control is performed based on the detection output, or the frequency band of access control is expanded, so unnecessary resonance of the mechanical system can be minimized. Some have adopted a special structure in order to move to a higher frequency range outside the control frequency band. However, since such a method employs various detecting means and a special structure in order to shorten the access time, the price of the disk device using this is expensive.

In a general optical disc apparatus, as shown in FIG. 2, a recording / reproducing head 2 is provided, for example, by a linear motor 5 so as to be movable in the radial direction (tracking direction) of the optical disc 1. Recording / playback head 2
Is provided with a light source and an objective lens (not shown), and irradiates the track 4 of the optical disc 1 with the light beam 3 to record and reproduce information. As a means for knowing the current position or moving distance of the recording / reproducing head 2, an output pulse of a linear scale 6 attached to the linear motor 5 or recording / reproducing head
A track crossing counter 7 for counting the track crossing signals detected by the reproducing head 2 is provided. A control unit 8 including a microcomputer is connected to the track crossing counter 7. The control unit 8 controls the entire optical disc device, and based on the position information from the track crossing counter 7, the speed information from the speed sensor 9 for detecting the moving speed of the recording / reproducing head 2, and the access target position, The access travel target speed is calculated. The access traveling target speed and the moving speed from the speed sensor 9 are given to the subtractor 10, where a difference signal between the two speeds is obtained. This difference signal is given to the driver 12 via the amplifier 11, and the driver 12 drives the linear motor 5 based on the provided difference signal. That is, the speed sensor 9 and the subtractor 1
0, amplifier 11, driver 12, and linear motor 5
In this, a speed control loop is formed, whereby the speed of the linear motor 5, that is, the moving speed of the recording / reproducing head 2 follows the access travel target speed instructed by the control unit 8.

In such an optical disk device, the access traveling target speed generally exhibits a waveform such that the first half is constant and the second half is decelerated, as shown in FIG. Then, the actual moving speed of the recording / reproducing head 2 that travels following this access traveling target speed is
As shown by the broken line, a triangular or trapezoidal shape is shown with respect to the access travel target speed shown by the solid line in FIGS. Of course, depending on the acceleration / deceleration method and the acceleration or access distance at that time, the shape of the isosceles triangle or the isosceles trapezoid as shown in FIGS. Here, the easiest way to shorten the access time is to increase the access travel target speed from Vr1 to Vr1 'or increase the acceleration of the access travel target speed (make the deceleration gradient steep).

[0005]

However, as described above, making the deceleration gradient of the access travel target speed steep means that the frequency components included in the deceleration gradient spread to a high range, and as described above. A corresponding frequency band (response) is also required for the speed control loop. Even if the access control target speed with a steep deceleration gradient is given to the speed control loop that does not have a sufficient frequency band, the recording / reproducing head 2 cannot move accurately following the target speed.
As shown in (a) and (b), an error occurs between the access traveling target speed and the actual moving speed of the recording / reproducing head 2,
The stop time of the recording / reproducing head 2 is also delayed by Δt1 and Δt2. Along with this, a distance error D occurs between the actual stop position (access position) es after the access traveling and the access target position e. If this error D is large, a great amount of time is required both when the access operation is performed again and when the track jump is performed instead of this access operation, which causes a hindrance to shortening the access time. Become. For this reason, the optical disc device is previously provided with a correction distance Δ for correcting the distance error D.
Generally, x is held in advance as a fixed table or the like. However, if the optical disk device changes over time after manufacturing the optical disk device, environmental changes such as temperature,
Depending on the difference in the optical characteristics of the optical disk medium used by the user, the degree of contamination, and the like, the value of the correction distance Δx determined in advance causes an insufficient correction amount, which hinders the shortening of the access time. It will be.
When the frequency band is sufficiently provided for the speed control loop, the frequencies of higher-order resonance and characteristic distortion of the linear motor 5, the speed sensor 9 and the like must be sufficiently higher than the frequency band. It is necessary to adopt high performance, that is, a special structure or material, or to provide a special compensator as the speed sensor 9 and other constituent members. For the same reason, it becomes necessary to use a lightweight linear motor 5 and a recording / reproducing head 2, which increases the price.

[0006]

The present invention has been made in order to solve such a problem, and takes into account the access correction distance Δx to the access distance x from the current position of the recording / reproducing head to the access target position. Then, the virtual access distance X is obtained, the access travel target speed Vref is obtained using the virtual access distance X, and the access travel target speed Vref is obtained.
After moving the recording / reproducing head so as to make the virtual access distance X zero, the actual access position of the recording / reproducing head is checked, and the access correction distance Δx is corrected based on the actual access position. It was done.

[0007]

Therefore, according to the present invention, for example, the actual access correction distance Δu is obtained based on the actual access position of the recording / reproducing head, and the access correction distance Δx and the actual access correction distance Δu are predetermined values. In the case of the above deviation, if the access correction distance Δx is rewritten to Δu, the access correction distance Δx becomes an appropriate value according to reality.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A method of accessing a disk device according to the present invention will be described in detail below.

FIG. 1A is a flowchart showing an embodiment of the present invention, and FIG. 1B is a flowchart showing details of the subroutine A (step 103) shown in FIG. 1A.

In this embodiment, the optical disk device shown in FIG. 2 is assumed. Also,
As in the conventional case, the access travel target speed shows a waveform in which the first half is constant and the second half is decelerated when the time axis is set horizontally.

The access procedure will be described below with reference to the flow chart shown in FIG. 1 with reference to FIG.

First, in step 101, the current position S0 of the recording / reproducing head 2 is checked, and in step 102, the access target position S1 is checked. Then, the process proceeds to step 103, and the access distance x is obtained as the difference between the access target position S1 and the current position S0 (step 201). x = (S1-S0) (1)

Next, the access correction distance Δx of the recording / reproducing head 2 calculated from the access distance x of the recording / reproducing head 2 is obtained (step 202). Δx = f (x) (2)

Then, the virtual access distance X of the recording / reproducing head 2 is obtained from the access distance x of the recording / reproducing head 2 and the access correction distance Δx (step 203). X = x + Δx (3) This corresponds to setting the access target position S1 as the virtual access target position S1 ′. That is, S1 ′ = S1 + Δx.

The access travel target speed Vref is obtained using the virtual access distance X (step 204). Vref = g (X) (4)

This access travel target speed Vref is given to the subtracter 10 and the track crossing counter 7 is monitored (to switch the access travel target speed Vref) until the virtual access distance X becomes zero (access travel target speed). Iterative calculation is performed thereafter until Vref becomes zero), and the access travel target speed Vref is continuously output (step 204).
~ 207). That is, if the time for traveling at the access traveling target speed VK is ΔtK, then X = Σ (VK · ΔtK)
Is intended.

As a method of obtaining the access correction distance Δx and the access travel target speed Vref, f (X)
In addition to the calculation with g (X) and g (X), the data may be stored in advance in the form of a ROM table, and the specific method is not limited.

Next, the actual access position Sr of the recording / reproducing head 2 is checked (step 104), and the actual access correction distance Δu is calculated from the current position S0 of the recording / reproducing head 2 before access (step 105). .. Δu = f (Sr, S0) (5)

Here, by verifying how much the access correction distance Δx of the recording / reproducing head 2 deviates from the actual access correction distance Δu, the access correction distance Δ is added.
It is determined whether or not x is updated (step 106).

For example, when the actual access correction distance Δu is greatly deviated due to the difference in optical characteristics of the optical disk medium or the degree of contamination, the difference with the access correction distance Δx becomes large, so that the update is necessary. Becomes That is, if the access correction distance Δx and the actual access correction distance Δu deviate by a predetermined value or more, step 1
At 06, it is determined that the access correction distance Δx needs to be rewritten, and the process proceeds to step 107.

At step 107, the access correction distance Δx
Is rewritten to Δu. As a result, the access correction distance Δ
x becomes an appropriate value according to the reality.

When it is determined in step 106 that the rewriting is not necessary, and after rewriting in step 107, the actual access position Sr and the access target position S
It is determined whether or not re-access of the recording / reproducing head 2 is necessary by comparing with 1 (step 108). If re-access is required, the recording / reproducing head 2 is precisely accessed (step 109). As a result, the recording / reproducing head 2
Accurately reaches the access target position S1 and stops.

[0023]

As is apparent from the above description, according to the present invention, for example, the actual access correction distance Δu is obtained based on the actual access position of the recording / reproducing head, and the access correction distance Δx is obtained. If the actual access correction distance Δu deviates from the predetermined value by a predetermined value or more, if the access correction distance Δx is rewritten to Δu, the access correction distance Δx becomes a proper value that actually matches the original access travel target speed. The access time can be shortened by setting a relatively high speed, and the distance of the inertial travel of the recording / reproducing head accompanying the increase in the access travel target speed and the change over time after the disk device is manufactured, Even with environmental changes such as temperature and differences in the disk media used by the user, the correction amount is sufficient to enable more accurate access operation. That. Further, since it is not necessary to provide a special compensation function or member in the disk device, it is possible to avoid the price increase of the disk device.

[Brief description of drawings]

FIG. 1 is a flowchart showing an embodiment of an access method for a disk device according to the present invention.

FIG. 2 is a schematic configuration diagram showing a main part of an optical disc device.

FIG. 3 is a diagram showing a general waveform of an access travel target speed.

FIG. 4 is a diagram showing changes in the actual moving speed of the recording / reproducing head with respect to the access traveling target speed.

FIG. 5 is a diagram showing changes in the actual moving speed of the recording / reproducing head with respect to the access travel target speed when the access travel target speed with a steep deceleration gradient is given to the speed control loop that does not have a sufficient frequency band.

[Explanation of symbols]

 1 Optical Disc 2 Recording / Playback Head 5 Linear Motor 6 Linear Scale 7 Track Cross Counter 8 Controller 9 Speed Sensor 10 Subtractor

Claims (1)

[Claims] 1. An access correction distance Δ from an access distance x from a current position of a recording / reproducing head to an access target position.
x is taken into account to obtain a virtual access distance X, the virtual access distance X is used to obtain an access travel target speed Vref, and the recording / reproduction is performed based on this access travel target speed Vref so that the virtual access distance X becomes zero. After the head is moved, the actual access position of the recording / reproducing head is checked, and the access correction distance Δx is corrected based on the actual access position. ..